/*
Problem:
The prime factors of 13195 are 5,7,13 and 29. What is the largest prime factor of a given number N?
e.g. for 10, largest prime factor = 5. For 17, largest prime factor = 17.
*/
#include <stdio.h>

int main() {
	int n = 0;
	scanf("%d", &n);
	int prime = 1;
	int i = 2;
	while (i*i <= n) {
		while (n%i == 0) {
			prime = i;
			n /= i;
		}
		i += 1;
	}
	if (n > 1)
		prime = n;
	printf("%d\n", prime);
}